The authors, Canadian freelance writers, here introduce three Jews who became assassins to dramatize Jewish persecution. In 1926 in Paris, Ukrainian-born Samuel Schwartzbard gunned down Simon Petliura, the anti-Semitic former leader of the Ukraine, during whose rule (1919-1921) between 50,000 and 100,000 Jews were murdered. Yugoslav David Frankfurter, in 1936, shot Wilhelm Gustloff, a Nazi leader in Switzerland, where sympathy for Hitler was growing. Herschel Grynszpan, a German, in 1938, assassinated a minor German diplomat in Paris. The first two men were acquitted by courts in France and Switzerland, respectively, while Grynszpan was most likely executed by the Vichy government. The authors, who do not address the problematic issue of ``violent justice,'' express praise for these assassins, for each man surrendered himself voluntarily to the authorities. (Dec.)